What are solar storms?Also known as a solar flare, a solar storm is a series of large explosions in the sun's atmosphere caused by magnetic instability.

"Large explosions" — how large?Sun storms have been recorded releasing as much as 6 x 10ˆ25 joules of energy — that's about a trillion times more powerful than the nuclear bomb that exploded over Hiroshima at the end of World War II.

What effect did this month's solar flare have on earth?The "solar tsunami" recorded on August 4 provoked nothing more extreme than a dazzling light show. But scientists say this could be the start of a low in the sun's 11-year life cycle, making this potentially the first in a long season of solar storms. More serious ones could cause immense damage to our infrastructure.

So our cell phones might not work?Correct. But a massive burst of energy could also fry electrical grids. Power in wide areas might fail, or surge dangerously, causing fires. Navigation systems — such as those on commercial airliners — could be disabled, and the global financial system brought to a grinding halt. "Little or no electricity means little or no telecommunications, refrigeration, clean water or fuel," warns Joseph in the New York Times. "Basic law enforcement and national security could be compromised." The resulting pandemonium could cost up to $2 trillion a year for several years, he warns.

Has it ever happened before?There was a "solar tempest" in 1859 that caused telegraph wires to short out across the U.S. and Europe, starting multiple fires. With today's modern technology, the effects would be much, much worse. A minor solar flare in 1989, for instance, caused a massive power outage across Quebec, Canada. In South Africa, a 2003 storm left parts of the country without power for several months.

Is there any way of stopping this?No, but scientists can put satellites and power grids on "safe mode" if they can figure out how to predict when a sun storm will occur. NASA is collaborating with the National Oceanographic and Atmospheric Administration to improve its space weather forecasting. A more fool-proof fix, argues Lawrence E. Joseph in the New York Times, would be "grid-level surge suppressors," which would shut down power grids much in the same way as our computer hard drives protect themselves in the event of a surge. But protecting America's 5,000 vulnerable grids could cost as much as $250 million.